1. Field of the Invention
The present invention relates to an extremely small illuminated switch that is constituted by adding illuminating means to existing components of a non-illuminated switch.
2. Description of the Related Art
[A] FIG. 1 is a cross-sectional side view of a known toggle switch for a printed circuit board.
On the left and right of the toggle switch, a clip-type switching mechanism is provided. A sliding rod 6 urged by a coil spring 5 disposed inside a central lever 2 provides a clicking sensation and functions as a switching indicator of the lever 2.
The size of the above-mentioned switch is small: wherein the terminal pitch is 2.54 mm and the size of the switch body is 7×4.5 mm. It is impossible to make an illuminated switch with this size by applying a known technology.
[B] FIGS. 2 and 3 are a cross-sectional front view and a cross-sectional side view, respectively, of a known illuminated switch. A switch body is constituted of a housing 13 and a base 17. At substantially the center of the head of the housing 13, a lever 12 functioning as a switch operating unit 12a is inserted through a through-hole 13a. A contact mechanism disposed on the base 17 includes a pair of fixed contacts 17a and a movable contact piece 18, which moves together with the switch operating unit 12a and is fixed to the lever 12. A light-emitting element 15 is also disposed on the base 17. The light emitted from the light-emitting element 15 is guided through and then diffused from the tip of the switch operating unit 12a composed of a transparent material.
An electronic apparatus, however, may include a plurality of reduced-size illuminated switches. In such a case, the designs of the external panels and the heights and positions of the electric components disposed on printed circuit boards differ. Therefore, in order to transmit the status of the components to an operator from the left, right, front, back, and upper directions of the illuminated switch, it is important to provide an extremely small illuminated switch that is easily visible.
An illuminated switch according to the above-mentioned related art [A] is too small to contain a space for disposing a light-emitting element and the wiring required for the light-emitting element. For this reason, a relatively high cost has been necessary for developing new components.
As illustrated in the cross-sectional side view of a known illuminated switch shown in FIG. 3, the illuminated switch according to related art [B] has the light-emitting element 15 disposed inside the switch body. The light emitted from the light-emitting element 15 is guided through the cylindrical switch operating unit 12a composed of a transparent material. Thus, the light is converged at the tip of the switch operating unit 12a, which is the end section of the illuminated switch, to brightly illuminate the tip. However, the viewable angle of the emitted light is narrow for such an illuminated switch. In particular, an illuminated switch having a switching mechanism in which the switch operating unit 12a is moved vertically is less visible compared to an illuminated switch having a switching mechanism in which the switch operating unit 12a is swung horizontally to improve its visibility.
The light-emitting element 15 illustrated in the cross-sectional view of a known illuminated switch shown in FIG. 2 is connected to the fixed contacts 17a by various methods, such as soldering, which applies thermal stress, and spot welding and swaging, which apply mechanical stress. Moreover, electronic apparatuses and electronic components may be connected by using a conductive adhesive having great heat resistance and fatigue resistance. Recently, such an adhesive has been used to prevent damage of the components when installing and to achieve a Freon-free, lead-free, and VOC-free environment. However, the optimal amount of conductive adhesive to be applied must be finely controlled by known production equipment and extremely fine adjustment is required for preserving the adhesive.